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Copy of Visual Perception Principles
Transcript of Copy of Visual Perception Principles
visual perception principles
Depth Perception cues
3. TEXTURE GRADIENT
5. HEIGHT IN THE
1. RETINAL DISPARITY
Remember: Visual sensation is physiological and the same for everyone with normal vision.
Visual perception on the other hand is both physiological and psychological in nature.
We now know how we ‘see’ an object, but how do we put together information to form a meaningful object?
Visual perception principles are rules or ‘laws’ which explain how one organizes and forms a coherent understanding of the retinal image, which is often incomplete and inconsistent in nature.
VISUAL PERCEPTION PRINCIPLES
refer to the way in which we organise the features of a visual scene by grouping them to percieve a whole, complete form.
When using this principle, we separate the important elements of the visual field (figure) from the surroundings (ground).
This is achieved by the observer separating the figure from the ground by using a contour.
The contour marks the boundaries of the figure.
Closure is the perceptual tendency to fill in or ignore gaps in sensory input and perceive objects as complete.
Similarity is the tendency to perceive stimuli with similar features (such as size, shape, colour, or form) as belonging together, or being part of a unit.
Proximity is the tendency to perceive parts of a visual stimulus that are close together as belonging together as part of a group.
111 1 111 1 111
When you look at the image above, all we should see is the number one repeated 11 times.
However, the law of proximity states that we will group parts of a visual stimulus that are close together as belonging together as part of a group.
DEPTH PERCEPTION CUES
MONOCULAR DEPTH CUES
BINOCULAR DEPTH CUES
Depth perception involves the ability to decode the information within the two-dimensional retinal images in order to gain a three-dimensional impression of our environment, including an idea of how far away objects are spatially located.
DEPTH CUES – are physiological or environmental indicators that help one establish a perception of depth and/or distance
Allow the judgement of distance and depth using one eye (mono means one).
Cues of this type occur in each eye and can operate independently of the other eye.
Is when the lens automatically focuses on an object by either bulging (near objects) or flattening (distant objects) and also allows continuing focus of moving objects.
The brain determines the depth and distance of objects by interpreting information about how much the lens bulges or flattens by the ciliary muscles.
Is the difference (disparity) between the retinal images (we have two eyes and therefore two retinas) of an object due to the 6-7 cm distance between our eyes.
Our brain automatically combines the images from each eye to enable the whole, three dimensional perception of objects.
When the brain compares the images, any differences between them provide information about depth & distance from the object from the viewer.
The greater the disparity (difference) between the retinal images, the closer the brain interprets the object to the viewer
Is the simultaneous inward turning of both eyes to focus on a nearby object (within 7 metres)
Our brain interprets the object of focus to be closer and closer as the tension on the muscles required to turn the eyes inward increases.
HEIGHT IN VISUAL FIELD
Is the apparent meeting of parallel lines as they recede into the distance, providing information about depth and distance.
Partial obscuring (blocking) of one object by a closer object.
As objects recede into the distance the visible detail diminishes (becomes denser and more finely packed) whereas up close, we can see more detail.
Therefore, objects that we can detect finer detail are perceived as being closer to us.
Is the use of other, or nearby objects to judge size in relation to them.
Objects that produce the largest image on the retina are perceived as closer and images that produce the smallest image are perceived as further away.
It is largely dependent on familiarity with objects
An object located closer to the horizon is perceived as being further away than an object located further away from the horizon.
Closeness of an object to the horizon also signals greater distance of the object from the observer.
The visual constancies create the tendency to perceive an object as remaining stable/unchanging despite changes that may occur to its retinal image due to variations in viewing conditions.
Allows us to recognize that an objects actual size remains the same even though the size of the image cast on the retina changes.
Is the tendency to perceive an object as maintaining its shape despite any change in the shape of the image of the object cast on our retina.
Is the tendency to perceive an object as maintaining its level of brightness relative to its surroundings, despite changes in the amount of light being reflected from the object on the retina.
Orientation constancy is the tendency to visually perceive the true orientation of objects in the environment even though the retinal image of the object may be at a different orientation.
CAMOUFLAGE MAKES CONTOURS HARDER TO SEE AND THUS, DISTORTS FIGURE (PERSON) FROM GROUND (THE BUSH)
Focus on the whiteboard and point your finger at the roof out in front of your face.
Move your hand with the finger upright toward the whiteboard and back to your nose
Notice how the double image of your fingers get further apart as your hand gets closer to your face. This is retinal disparity.
EX: If Ms. Marrello walked towards you from 50 metres away, her image would get larger – but thanks to size constancy, we know she is just getting closer, not growing taller with every step.
This Mustang GT is painted metallic midnight blue. However, it looks darker at night and lighter when the sun is on it. Nevertheless, thanks to brightness constancy, I know it’s the same Color.
Ex: When we are lying down, things look different (at a different angle) from when we are standing. But we still know it is the same object.
The predisposition, or ‘readiness’, to perceive something in accordance with what we expect it to be.